You'll be fine with PNP, as long as you accept that when the 555's output is high, the load will be off and when the output is low, the load will be on.
I think 80mA of base current is overkill and at 12V would require a huge 1W base resistor which is ridicules.
With a forced beta of 10 and a current of 1A, the collector saturation voltage is 100mV, which is more than good enough for a 12V load so we can stand it being a bit higher, if it means the base current is lower.
I reckon a base current of 40mA will be fine, so use a 270R base resistor, if the 555 is powered from 12V. The resistor will need to be rated for 0.5W, if the duty cycle is 100% but it can be derated if the duty cycle is lower.